1. Field of the Invention
This invention pertains to the field of radiology generally, and more specifically to an improved apparatus and method for displaying radiological information such as anatomical images in a manner closely emulating light boxes, but having additional features and advantages available from computer image processing.
2. Description of the Related Art
Radiologists have traditionally reviewed X-ray photographic images on light boxes, sometimes also referred to as view boxes. These photographic images may be directly formed onto appropriate film stock by illuminating an anatomical region with X-ray radiation and then developing the film. Once developed, the film may be displayed directly on a light box. A radiologist will manually manipulate the images, including flipping the images top to bottom and left to right and also rotating the images, without looking away from the image. This is done by grasping an edge of the image and either flipping the image over to form a mirror image thereof or by rotating the image clockwise or counter-clockwise to view a rotated image. One image may be placed directly over another for visual comparison, and sequences are readily rearranged. Each of these manual actions is easy to perform and quite intuitive with the actual film stock. As a result, the film stock and light box is very convenient and easy to use, and most radiologists have grown accustomed to this system.
More recently, equipment has been developed which is capable of providing a radiologist and various other medical personnel with different views of the same physiology. Depending upon the symptoms a patient may present, imaging systems such as CT scans and/or MRI may be selected as appropriate diagnostic tools. Multiple images of sequential body sections may be generated, and duplicate sequences of the same body sections may be created with varying degrees of exposure intensity. By varying exposure intensity, a radiologist may be able to discern features from two contrasting sequences which might otherwise not be visible in either single sequence. These newer diagnostic imaging systems may generate electronic representations of the actual image, and these electronic signals may then be outputted to one or more media for viewing and storage. Often, even with electronic capability, the information from these newer diagnostic tools is outputted to transparencies for handling and review by the radiologist on the familiar light box.
Unfortunately, the radiologist loses some advantages that are inherent in the electronic system when the image is converted to "hard-copy" such as a transparency. Since the film stock is generally exposed at actual size, smaller details or features may be difficult to identify or interpret accurately. Images are not easily magnified to focus in on a particular feature, and special computer image processing features such as edge detect, sharpening and other techniques are unavailable. Furthermore, storage of images and sequences of images requires substantial filing space and expensive record archiving. Where a further review by other medical personnel is warranted, film stock is difficult to transmit and must be manually copied and delivered via a courier. The reviewing personnel are then also limited to views and magnification selected by the first reviewer. To further compound the challenges of hard-copy, many new diagnostic imaging systems are capable of generating hundreds of helpful, separate images in a single sequence. Handling the large quantities of images in hard-copy becomes quite cumbersome.
In an effort to circumvent the need for generating hard-copy, a number of computer systems have been developed which allow the radiologist to directly view the actual images for evaluation. These computer systems allow the radiologist to take advantage of a number of features available only through computer graphics presentation of the anatomical data, more commonly referred to as "soft-copy". Computer software is well known and widely available for performing a variety of image manipulation functions such as angular rotations, image flipping, edge detection, zooming or selective magnification, and sharpening. Unfortunately, much of the software was originally developed for graphic artists and others specializing in the development and manipulation of the content of images. In many cases, a radiologist does not need to create or substantially alter the image, but instead needs to be able to manipulate the image as easily and intuitively as possible. As a result of the differences between the way a graphic artist handles an image and the way a radiologist would handle the same image, many radiologists still prefer to work with film stock or computer generated transparencies and the traditional light box.
The prior art has disclosed various improvements which adapt the computer systems more specifically to the handling of anatomical data and for use by medical personnel, but these improvements are not completely satisfactory.
For example, Hilton et al in U.S. Pat. No. 5,452,416, incorporated herein by reference, proposes a multi-head workstation, meaning that more than one video display monitor is used to display radiological data. The system offers numerous features which are becoming more commonplace in radiological viewing systems, including database management, exam scheduling, fixed-site and mobile image input, case review, reporting, teleradiology, electronic delivery of images/reports (voice and text) to referring physicians' offices, printing, operation with LANs and WANs, integration with other information systems, automated image display based upon radiologists' individual preferences, automatic output based upon referring physicians' individual preferences, automated printing, and displaying of cines (cinematographic presentations of sequences of images).
Unfortunately, however, the Hilton et al system still requires a separate monitor on which a variety of menus and control icons are displayed. The additional monitor adds undesirable expense and desktop size to the system, but far more consequential than cost or space is the way a user must interface with the displays. For example, if when looking at an image, a radiologist identifies an area requiring more attention and wishes to put the image in different anatomical perspective, the radiologist must visually leave the area of interest, look at the separate monitor, find the necessary control to alter the image, and then return to the image on a different display screen. In leaving the radiological image, the radiologist is bound to lose track of the original area of interest and must locate the area once more. This can be a very frustrating waste of time, particular for those medical personnel who are accustomed to using the light boxes and film negatives, where the film may be grasped and manipulated without ever visually leaving the area of interest. As a result, many medical personnel still use hard-copy and resort to soft-copy viewing stations only for special applications and requirements.
A number of other systems are cited in the Hilton et al patent, each of which are also incorporated herein by reference for their enablement of the standard and basic features and functions necessary to implement a computerized radiological display system. Moreover, a number of these systems are available commercially that illustrate similar basic functionality. Nevertheless, none of these systems illustrates or teaches an apparatus or method which allows a user to truly emulate viewing film on a light box and still obtain additional benefits available only from soft-copy.